Coastal Plains Ecoregion - National Lakes Assessment Results

• Key results
• Change from 2017

Key Results

An estimated 77,427 lakes in the Coastal Plains ecoregion are represented in the National Lakes Assessment (NLA). Of these lakes, 19% are natural and 81% are man-made.

The NLA uses trophic state as an important indicator of lake condition and assesses the extent of biological condition and key stressors in the nation’s lakes.

• In the Coastal Plains, 22% of lakes are rated as hypereutrophic while 56% are eutrophic, 16% are mesotrophic and 6% are oligotrophic.
• The most widespread stressors assessed are atrazine detection, phosphorus, and lakeshore disturbance with 42%, 27% and 26% of lakes in poor condition respectively.
• Cyanobacteria are one-celled photosynthetic organisms that normally occur at low levels. Under eutrophic conditions, cyanobacteria can multiply. Not all cyanobacterial blooms are toxic, but some may release toxins, such as microcystins. For information about risks at specific locations, recreational water users should check with state, tribal or local governments.
  • Based on microcystins, detections occurred in 45% of lakes and no lakes were above the recreational benchmark.

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Change from 2017*

• For the Coastal Plains, the NLA reports that the percent of lakes in good condition for benthic invertebrates increased by 16 percentage points between 2017 and 2022. 
• The percent of lakes with atrazine detections increased by 33 percentage points and the percent of lakes with microcystin detection increased by 20 percentage points.

To access more ecoregional specific information, please visit the interactive NLA Dashboard.

* The change analysis is based on information from two points in time – 2017 and 2022.